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Subsurface Results <br /> Byron Road Trenching Alignment, Tracy California <br /> 2. Field Results - Borings <br /> 2.1 On Thursday, March 13, 2003, ECM directed the completion of 17 soil borings at <br /> the site. Boring locations are shown on Figure 2 (Appendix A). The borings were <br /> spaced 100 ft apart along the proposed trench alignment. Some boring locations <br /> were moved either east or west along the alignment to avoid existing utilities or to <br /> provide data for the planned junction vaults. <br /> 2.2 A boring could not be completed near the planned connection vault at the east <br /> end of the proposed trench (near Corral Hollow Road). This boring could not be <br /> completed because the future vault is sited under existing overhead power and <br /> telephone lines. These overhead lines constitute a safety hazard for drilling <br /> equipment. <br /> 2.3 Two hollow-stem auger drilling rigs were used to complete the borings. Each <br /> boring was completed to a depth of approximately 12 ft below grade, except for <br /> borings B-2 and B-3, completed to 10 ft below grade. At least one soil sample <br /> and one ground water sample were collected from each boring. <br /> 2.4 Ground water was encountered in each boring, at a consistent depth of about 10 <br /> ft below grade. Soils were typically logged as silty sand fill in the upper 1 to 2 ft, <br /> underlain by clayey silts and silty sands to the bottom of each boring. A visual <br /> classification log for each boring is included as Appendix B. The logs include the <br /> approximate depth of ground water, and readings collected from the field <br /> monitoring instrument (photoionization detector, or PID). <br /> 2.5 Each soil and ground water sample was analyzed for gasoline and BTEX <br /> compounds (benzene, toluene, ethylbenzene and xylenes), diesel, and motor oil. <br /> Selected samples were also analyzed for polynuclear aromatic compounds <br /> (PNA/PAH) by EPA Method 8270. <br /> 2.6 The analytic results for the sampling work are shown on the attached Figure 2 <br /> (Appendix A). Laboratory analytic reports are included with this report in <br /> Appendix C. <br /> Page 2 of 4 <br />